The present invention relates to a figure eight descender. More particularly, the invention relates to a figure eight descender that can prevent inadvertent slipping of a rope from the descender.
There are many implementations of a figure eight descender by prior art.
FIG. 1 shows a figure eight descender 10 by prior art. The figure eight descender 10 has a top ring 12 and a bottom ring 14 connected by a neck 16. A user makes a loop of in the middle of a rope 18, and pushes the loop through the top ring 12. Then the user pulls the loop over the bottom ring 14, and pulls the free end of the rope 18 so that the loop is tightly wound around the neck 16. The bottom ring 14 is for connection with a carabiner. The figure eight descender 10 holds the weight of a climber. One end of the rope 18 is connected to an anchor, while the other, free end of the rope 18 is grasped by the climber to control his or her rate of descent. The contours of the top ring 12 and the bottom ring 14 change smooth, and when the rope 18 is loose, there is a danger that the rope 18 might slip upward from the top ring 12 or downward from the bottom ring 14.
FIG. 2 shows another figure eight descender 20 that has a top ring 22 with two ears 24, a bottom ring 26, and a neck 28 connecting the top ring 22 and the bottom ring 26. While the ears 24 prevent slipping of a rope upward from the top ring 22 to some degree, it cannot prevent downward slipping of a rope.
U.S. Pat. No. 316,870 by Braunfeld discloses a fire-escape that is similar to the figure eight descender 20 but smaller.
U.S. Pat. No. 4,678,059 by Bowker discloses a rope descending device that includes an oval ring, a rail mounted on the ring, and a clasping means that spans the width of the ring. A rope passes the ring in a way different from that related to descenders 10, 20.
U.S. Pat. No. 4,723,634 by Fisk discloses a rappelling device that includes three integral eyes or rings. A rope is wound around the eyes in various combinations. A finger and a line guide, which are similar to the ear 24 of the descender 20, are provided and may be used to prevent upward slipping to some degree.
U.S. Pat. No. D-458,533 by Sonju discloses a tether coupler that is practically the same as the descender 10.
U.S. Pat. No. D-376,095 by Curtis discloses a rappelling device that includes one ring and four ears. The ears are used to hold a rope rather than to prevent slipping.